Electric cable



` Nov. 24, 1942m s. BURGETT 2,302,839

ELECTRIC CABLE Original Filed March 14, 1940 3 Sheets-Sheet l INVENTQR.

Nov. 24, 1942. L. s. BURGETT 2,302,839

ELECTRIC CABLE l original Filed Maren 14,' '1940 3 sheets-sheet 2 INVENTOR.

Nov. l24, 1942. f ls, BURGETT 2,302,839 ELECTRIC CABLE l l I original Filed march 14,v 194C s sneetysneap s Eatented Nov. 24, 1942 ELECTRIC CABLE Lynn S. Burgett, Euclid, Ohio, assignor to The Clark Controller Company, Cleveland, Chio, a

corporation of Ohio Original application March 14, 1940, Serial No.

323,971. Divided and this application September 12, 1940, Serial No. 356,462

2 Claims.

This invention relates to electric cables and terminals therefor, and particularly to cables for carrying current of great amperage, and constructed to be flexible.

Cables of the class referred to are used for various purposes wherein the current to be conducted by the cable is of great amperage and wherein the cable must bend in use, one illustrative use being to conduct welding current to a movable welding gun or machine, in which case any lack of flexibility in the cable would interfere with the fre movement of the gun by the operator thereof.

The invention comprises various improvements over prior cables of this class, which appear in the following objects of the invention.

It is among the objects of the invention:

To provide generally an electric cable of relatively great amperage capacity having an improved quality of flexibility;

To provide generally an electric cable having improved means for conducting cooling fluid,

VAsuch as liquid, therethrough;

To provide in a cable of the multi-conductor class an improved construction of terminal for the ends of the conductors by which electric connections may be made to the conductors of the cable; and/or by which cooling fluid may be introduced into and circulated through the cable; and/or admitting of the practice of an improved method for securing the ends of the cable conductors to the terminals;

To provide for multi-conductor cables of the liquid cooled type, improved means for insulating the conductors one from the other and for providing cooling liquid passageways through the cable;

To provide an improved construction of insulator for the conductors of a multi-conductor electric cable.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed in the following description taken in connection with the accompanying drawings, in which:

Figs. 1 is a side elevational View of an electric cable embodying my invention, and illustrating one construction of terminal at the ends thereof; Fig. 2 is a longitudinal sectionalview of the right hand end of the cable of Fig. 1 and drawn to enlarged scale;

Fig. 3 is a sectional view taken from the plane 3-3 of Fig. 2 and with some of the parts thereof omitted for simplicity;

Fig. 4 is a view taken in the direction of the .arrow 4 of Fig. 2;

Fig. 5 is a cross-sectional view taken from the plane 5-5 of Fig. 2;

Figs. 6 and 7 are respectively plan and crosssectional views of an insulator which I may employ in the cable of Fig. 2, Fig. 7 being taken from the plane 'l-'l of Fig. 6, and these views illustrating the sheet form in which the insulator is first made, the aforesaid Fig. 5 illustrating the insulator in its assembled condition in the cable;

Fig. 8 is a View in some respects diagrammatic -for clearness, illustrating the overlapping of opposite edges of the insulator of Fig. 7 when it is assembled in the calole as in Fig. 5;

Fig. 9 is a view, a part of which is in elevation. a part of which is in longitudinal section, and a part of which has an outer portion broken away, illustrating the construction of an outer casing or hose of the cable of Fig. 2;

Fig. l0 is a View similar to a part of Fig. 9 illustrating a modification;

Fig. 1l is a cross-sectional view taken from the plane Il-II of Fig. 9;

Fig. 12 is a view similar to a part of Fig. 2 and illustrating certain steps of method which I may employ in securing conductors of the cable to a terminal thereof, the view being taken approximately on the plane l2| 2 of Fig. 4;

Fig. 13 is a view in elevation illustrating a modified form of a terminal connector;

Fig. 14 is a view illustrating in longitudinal section another modiiication'of one of the terminals of Fig. 2 or of Fig. 13.

Referring to Fig. 1 of the drawings, I have shown at I the cable proper, and at 2-2 end connectors therefor. The connectors 2--2 may be alike or different, as will appear hereinafter, but as shown in Fig. 1, the connectors are alike and each comprises terminals 3 and 4 insulated from each other by an insulator |05; and threaded openings IDB- |06 are provided in the opposite connectors 2 whereby cooling fluid may be conducted into the cable at one end and out at the other. The terminals 3 are connected'to one set of conductors in the cable, and the terminals 4 connected to another set of conductors, and as will be explained hereinafter, the terminals 3 and 4 may be constructed in various types to adapt them to be connected to Various types of apparatus, such for examplefas a transformer at one end of the cable and a welding gun at the other end, when the cable is to be' used to carry welding current.

The right hand connector 2 and the corresponding end of the cable are shown in longitudinal section in Fig. 2, and coordinate therewith, the terminals 3 and 4 are shown in Figs. 3 and 4 in elevation.

The main body of the cable as shown in Figs. 2 and 3, comprises a plurality of conductors in groups alternately arranged, as for example at 5 5 5 and 6 6 6 in Fig. 5; and disposed around a longitudinal core of rubber or the like 1; and insulated from each other by a convoluted insulator 8 of rubber or like flexible insulating material, and surrounded by a tubular casing or hose 9.

The conductors 5 and 5 are preferably made up in a well known manner, of thread wires and strands woven or twisted into rope form to render them flexible.

To simplify the drawings, particularly Fig. 2, the conductors 5 and 6 are illustrated as lying parallel to the axis of the cable, and in fact, may be disposed in this relationship, but'l I prefer to dispose the conductors in helical arrangement around the exis.

In assembling the conductors 5 and 6, and the insulator 8, the conductors B Gmay first be laid around the core l, and the insulator 8 laid thereon; and the conductors 5 5 then laid in convolutions in the insulator, to be presently described, and then the casing or hose 9 is telescoped longitudinally over the insulator and conductors, the hose or casing being shorter than the insulator and conductors, so that the latter project out of the opposite ends thereof.A

The insulator 8 is shown in Figs. 6 and 7 in the form in which it is first made. Preferably it is made from rubber by an extrusion or other process into generally planar or sheet form, comprising flat or planar portions Ill-I0, and spaced loop portions or corrugations I I II between the planar portions, and in the present illustrative instance, where there are to be three conductors 5 5 5, there will be three such convolutions. The corrugations comprise parallel side walls I4 I4 joined to adjacent planar portions I O I 0, and the side Walls are connected by anoutwardly convex portion Il. The outermost planar portion I at each side of the insulator, terminates in bent thinned edges I2 and I3. The sheet 8 may be made of considerable length, and at the time of making a cable of any chosen length, a piece from such long strip is cut off to approximately the necessary length, to be referred to, and is then folded around the core I to cause it to take up the cross-sectional shape shown in Fig. 5, wherein the loop portions II are disposed so that the conductors 5 5 may be laid therein and whereinI the planar portions I0 I0 bend so that they define a longitudinal cylinder firmly or tightly engaged with the inner wall of the hose 9 when telescoped thereover, as plainly shown in Fig, 5. The edges I2 and I3 of the strip, when bent into the form of Fig. 5, are disposed approximately as shown in Fig. 8.

Bending the sheet insulator from the form of Fig. 7 to the condition in Fig. 5, causes the convolutions II, as shown for one of them in Fig. 5, to become divergent, and causes the side walls i4, Figs. 5 and 7, of each convolution to be dis- .posed generally radially, as shown in Fig. 5.

It follows that when the core l, insulator B,

conductors 5 5 and 6 6 and the outer sleeve or cover 9 are assembled as shown in Fig. 5, or Fig. 2, there are longitudinal passageways I5 I 5 along the sides of the conductors 5 5, and longitudinal passageways I6 I6 along the sides of I'Ill the conductors 5 6, the passageways I5 I5 being separated by the insulator l from the passageways I5 I6, and the conductors 5 being insulated from the conductors 5.

If the conductors 5 5 and 6 5 are to be disposed in helical arrangement around the core, the sheet B is folded around the core 'l so that its edge portions overlap on a helical zone thereby disposing the convolutions II in helical arrangement.

The assembled cable proper, made as above described, is now joined to the connectors 2 2 as follows, and as shown for one of them in Fig 2.

The terminal 3 is joined to a head Il, preferably by being made integral therewith as a casting of copper or other highly electrically conducting material, and a material to which solder or other fusible metal will adhere, for a purpose to be described. The head I1 comprises a central cylindrical opening I8, the periphery of which is outwardly radially recessed by a plurality, such' as three, circular recesses I5 II, and inwardly toward the cable proper and beyond the recesses, the head I 'l has an annular shoulder 20, into which is fitted and secured, for example by soldering, a short tubular sleeve 2|, slightly larger in outside diameter than the inside diameter of the outer hose or casing, and larger on its inside diameter than the diameter of the assembled conductors and insulator. The head I'l is also provided with a plurality of threaded holes 22.

For the next step of the assembling operation, the conductors 5 and i and the insulator l are telescoped or projected through the sleeve 2| and opening I8 oi' the head Il, and the hose 9 is concurrently telescoped over the sleeve 2I, which stretches it tight thereon, to seal it liquid tight therewith, and it is further sealed and secured thereon against displacement by a wrapping of wire shown at; 23, Figs. 1 and 2. The outer conductors 5 5 are now bent outwardly radially, as shown at 24, Fig. 2, and laid in the recesses I5, and an assembling sleeve 25 is telescoped into the opening I8 substantially fitting the same and forcing the ends of the conductors into the recesses I9, the walls of the recesses and adjacent parts of the sleeve 25 constituting pockets into which the ends of the conductors are firmly lodged. 'I'he three conductors 5 are disposed in this manner and their end portions which extend beyond the head I1 are then cut ofi' as at 26 preferably flush with a transverse plane 21 on the head I'l. Solder or other fusible metal is then applied by well known heating means to the ends of the conductors 5, at 25 in the recesses I9, to securely join the wires thereof together, and to integrally unite them with the head I'I at the walls of the recesses I 9.

The other terminal 4 comprises a head 28, Figs. 2 and 4, having a transverse planar face 29, and an interior recess 30, and an inwardly open pocket 3|. The ends of the conductors i are now cut of! as at 32, Fig. 2, to a measured length beyond the plane 2l referred to, and the face 29 of the head 28 is placed upon the face 2l of the head Il with an insulating washer |05 therebetween, and bolts 34 34 are projected through insulating sleeves 35 in the head 28 anciv through perforations in the insulator 33 and threaded into the threaded holes 22 to rigidly seal and clamp the head 2B upon the head I1 wlith the ends'of the conductors 5 in the pocket 3 The head 28 has a plurality, such as two, pipe threaded openings llli iiliil, extending thereau through and communicating with the chamber 30.

The threaded openings |08 and 108A may be variously disposed. As shown in Fig. 4, in the form illustrated, they are disposed at an angle of approximately 120 degrees with each other but may, as will be understood, b'e disposed diametrically opposite, or otherwise.

Before the head 28 is bolted on, as described, the insulator 8 is cut of! at a point within the chamber 3|), for example, as shown at 36, short of the pocket 3|.

For the next step of' the assembling operation, the cable, illustrated thus far in horizontal position, is supported vertically, as indicated in Fig. l2, which disposes the pocket 3| at the lowermost point of the head 28. By means of a blow torch or other heat supplyingmeans 31, the head 28, and particularly the pocket 3| thereof, are heated, thus heating the end portions of the conductors 5 5; and a wire or stick 38 of solder or other fusible metal is projected through one of the said pipe threaded openings, for example the opening |06, and into engagement with the hot head 28 and conductors 5, and the solder melts and flows around the conductors filling the pocket 3| therearound and up to a level such as that shown at 39 joining the conductors to each other and to the wall of the pocket. This operation may be viewed through the other opening IBSA, and the filling with solder may therefore be stopped at a suitable observed level 39.

Upon removing the source of heat, and the soldering stick 3B, the solder sets and integrally joins the conductors 5 to the head 28.

The opposite end of the cable is assembled in the same way as that just described. The electric circuit through the cable will be seen to be from one of the terminals, say the terminal 4, from a current source, through the inner conductors 6, out at the other terminal 4, to apparatus to be energized and back therefrom through the terminal 3, and through the outer conductors 5, to the other terminal 3, and to the source, as an illustrative use.

Cooling liquid may be circulated through the cable. By one method, one of the openings, say |06A, is closed by a plug 40, Fig. 4, and a cooling liquid conduit has a threaded terminal thereof threaded into the other opening |08. Cooling liquid therefore will enter the chamber 30 and there divide, part flowing around the conductors 6-6 and longitudinally through the passages ||-|6, and out through a corresponding cham.-a ber and conduit at the other end of the cable; and part flowing from the chamber 30 through the opening I8, and longitudinally through the passageways |5|5 and out at the other end of the cable; thus flowing in two streams, each stream in direct contact with the metal of the conductors of one of the groups of conductors, and each stream insulated from the other by the insulator 8 through the major part of the cable.

The assembling sleeve 25 may be left in the position of use, and as illustrated in Fig. 2, or after the conductors 5 have been soldered into the recesses I9, it may be removed.

The terminals 3 and 4 are in the form of lugs with open ended slots to receive bolts for clamping them on to an apparatus part.

In Fig. 13 is illustrated a modification, in which the heads HA and 28A and the insulating washer |05 and bolts 34 and sleeve 2| are similar to those in the form of Fig. 2, but the terminals thereof it. .l it head 28A is in the form or a longitudinally ere-- tending tongue 4l; having a perforation t2 there= in by which it may be holte-d to a ceintoi use. tannini/il. to t l l provided with faces 44, 45, t5 and bolt holes tl and 48 and a threaded bolt hole 53; laminated flexible conductors matr therefore be bolted to this terminal by bolts proiecting through the bolt hole 48, or into the threaded bolt hole 53, and the laminated conductors lying against one of the faces 44 te 45 in a well known mami', or the terminal 43 may be bolted to a point of use by a bolt through the hole 4l.

In Fig. 14 isillustrated a modification of the outer head 28B corresponding to the head 28.

This head has the chamber 3! and pocket 3| and holes 49 for the bolts, as in. the form of Fig. 2.

-The electrical terminal 50 projects axially from Referring now to Figs. 9, 10 and l1, which illustrate more particularly the construction of the outer hose vor casing shown at 9, in Figs. 2 and 5, the hose is seen to comprise an outer layer or tube 53, and an inner tube of rubber 54, with a layer of cord therebetween. In prior hoses. threads or small cords of woven aramgement have been disposed between inner and outer layers of rubber. In some cases, because of the woven character of the threads, the threads extend longitudinally of the hose or in helical direction therethrough, some following a right hand helix and others a left hand helix. In some cases, be cause of the woven character of the threads, some of them extend substantially parallel to the axis and other helically around the hose. In either case, and in all prior hoses of which i2 have knowledge, when the hose bends, at least some of the cords `or threads of the fabric are put under tension, which resists the bending ci the hose and renders it stiff and of little flexibility, and causes the bent hose toy buckle and assume an elliptical cross-sectional form.

In the hose of the present invention, the thread or cord 55 is solely helical, having no parte that are put under tension when the hose bends, and the hose therefore has substantially the same flexibility as if it were made wholly' of rubber and without the reinforcing thread or cord, and may be bent upon a relatively short radius without deforming its circular cross section and when used as the covering hose or casing of a cable auch that described above, increases enormously the flexibility of the cable, over prior cables. For en ample, as an experiment I have found that a sixconductor cable, constructed and assembled comz plete as described hereinbefore and as illustrated and of such a size that the outside diameter of the assembled hose is 1% inches, can be Wrapped freely spirally around a 6 inch diameter pipe without materially distorting the cross-sectional circular form. The helical cord 55 at the same time pre vents distortion of the casing by cooling fluid under pressure' Furthermore, the cable is ren1 dered flexible in the torsional direction by the hose of this construction. A cable such as that illustrated and of 1% inches outside diameter and say 8 feet long can be twisted merely by the force of the human hands to approximately 450 degrees from normal in the direction that winds up the helix of the conductors for the usual helical angle thereof and 720 degrees from normal in the other direction.

In Fig. 9, I have illustrated the cord 55 as being a single cord, such as a cord of cotton, but it will be understood that the cord may be made of multiple parallel strands, or threads.

In making the hose of Fig. 9, a suitable process is to extrude the inner tube 54 and mount it on a mandril and then wind the cord 55 helically thereon, at such a pitch that there is a space 56 between adjacent convolutlons. The space may be commensurable with the diameter iof the cord.

Then an extruded outer tube 53 is telescoped over the cords. Then the two tubes are vulcanized together, being thereby integrally united through the cord convolutions and on the portions 56 between adjacent convolutions.

In the modification Fig. 10, the cord 55A is wound at such a pitch that adjacent convolutions of the cord touch or substantially touch each other and the outer and inner tubes 50 and 54 are vulcanized together primarily through the fibers of the cord.

My invention is not limited to the exact details of construction illustrated and described.

by my co-pending applications, Serial Number 359,107, filed September 30, 1940 for improvements in Methods of making cables, and Serial Number 356,463, iiled September 12. 1940, for improvements in Electric cables.

I claim:

1. In a cable, a plurality of longitudinally extending conductors; the conductors being arranged so that in cross section they are in generally-a circular series, with alternate conductors constituting one group and the other conductors another group; a longitudinally extending lnsulator of flexible insulating material disposed so that in cross section it comprises substantially radial portions, between each conductor and the next adjacent conductor, alternate pairs of which radial portions are joined by circular portions outwardly of each of the conductors of the said other group, and concentric with the axis of the cable, and the other alternate pairs of which are joined by outwardly concave portions inwardly of each of the conductors of the said one group; and a tubular casing telescoped over the said oircular portions of the insulator and over the conductors of the said one group, and longitudinal coolant passages between the conductors of said one group and the casing, and between the conductors of said other group and the said circular portions and between the conductors of said other group and said radial portions.

2. An insulator for multi-conductor cables comprising an elongated sheet oi' flexible insulating material comprising a plurality of spaced longitudinally extending corrugations alternating with a plurality of spaced longitudinally extending planar portions each corrugation comprising a pair of parallel spaced side walls joined respectively to adjacent planar portions and the pair of side walls being'connected by an outwardly convex arcuate portion,

LYNN S. BURGETT. 

